1. Field of the Invention
The present invention relates to an automatic document feeder mounted in an office machine, such as a fax machine, a scanner, a printer, a copy machine, or a multi-function peripheral (MFP), etc. to convey a document into or out of the office machine.
2. The Related Art
An automatic document feeder is widely used in an office machine, such as a fax machine, a scanner, a printer, a copy machine, or a multi-function peripheral (MFP), etc. The automatic document feeder conveys a document into the office machine to have an image handled, and then, the automatic document feeder transports the handled document to the outside of the office machine.
Referring to FIG. 1 providing a conventional automatic document feeder 200, the automatic document feeder 200 includes a feeding roller unit 70, a drawing-out roller unit 80 and a document-feeding passage 90. After the document enters the document-feeding passage 90, the feeding roller unit 70 including a feeding driving roller 71 and a feeding idle roller 72 gearing the feeding driving roller 71 feeds the document to an image-handling unit to have an image handled. Then, the drawing-out roller unit 80 involving a drawing-out driving roller 81 and a drawing-out idle roller 82 gearing the drawing-out driving roller 81 delivers the handled document to the outside of the document-feeding passage 90. Because the automatic document feeder 200 has the feeding roller unit 70 and the drawing-out roller unit 80, two pairs of gear wheels which are driven by a power machine such as a motor (not shown) are needed to mate with the feeding roller unit 70 and the drawing-out roller unit 80 respectively for carrying the document forward. Therefore, the structure of the automatic document feeder 200 is rather complex, and what is more, the manufacture cost and the difficulty of fabricating the automatic document feeder 200 are increased.
Referring to FIG. 2 representing an improved automatic document feeder 300, the automatic document feeder 300 has a document-transporting roller 100 instead of the feeding driving roller 71 and the drawing-out driving roller 81 (shown in FIG. 1). The document-transporting roller 100 gears a feeding idle roller 73 to feed the document to an image-handling unit to have an image handled. And at the same time the document-transporting roller 100 gears a drawing-out idle roller 83 to deliver the handled document to the outside of a document-feeding passage 91. Although the automatic document feeder 300 needs a pair of gear wheels driven by a power machine such as a motor (not shown) to mating with the document-transporting roller 100, simplifying the structure of the automatic document feeder 300 and reducing the manufacture cost thereof, however, the automatic document feeder 300 has only one document-transporting roller 100 to gear the feeding idle roller 73 and the drawing-out idle roller 83 simultaneously, increasing a drawing-out angle of the document, and then, the document is drawn out of the document-feeding passage 91 not smoothly.